This circuit is from General Electric documentation from 1970. The transistors can be of general-purpose types, except for the power that can be a BD136.
This circuit of a 1978 American publication monitors a telephone line by triggering a relay. The...
This interesting FET-tester circuit was obtained from an old American documentation. The bipolar...
This old VHF TV booster that also serves FM was found in Radio Electronics magazine from April...